High-frequency signaling system



"c, A. Hoxu-z HIGH PREQUBMY'SIGNALING s'xfs'ru I Sept. 11g-1923. 5 1 1'467'988 Filed March 16 i922 -T'Invehtor: ,'*Charles A.Hoxe,

b9 His Attorney- Patented Sept. lil, 1923.

unirse srarss ,e

sonreir?, s. consommer; or new Yong. y v y j A HGH-FBEQUEECY SIGHALING SYSTEM.

Appuuon and time '16,' 192.2. seran m. 544,155.

To all `wlwfm. t mag.; concern.'

Be it known that I, CHARLES A. Hoxrn,

'a citizen of the United States, residing at My presentinvention relates to signaling systems and more articularl to a system for receiving and etecting high frequency signals such. for example, as those which are employed in the wireless transmission of intelligence.

One of 'he objects of my invention is to provide a simple and eiiicient means for detecting high frequency signals. A more specitic object of my invention is to provide a means for detecting signals' produced by means of high frequency continuous currents. s

In the specification which follows, I have described my invention with particular ref; crence to radio signals. It will Abe understood, however, that it is no't limited in its usefulness to that particular field, but that,

it may eguali .well be employed for the detection o hig i frequency signaling currents which are transmitted over wire lines.

In carrying my inventionl into effect, I employ in a circuit upon which thelsignalingwaves may he impressed, a light sensitive device or devices which has the property of permitting current to flow therethrough when an electrode thereof is subjected to the influence of light. I also provide means for varying or interrupting the illumination of this device in such a way that the signaling current flowing in the circuit may be interrupted periodically in a.

i predetermined desired manner, and a rectifying effect may thereby be produced which will cause the current flowing in the circuit to be capable of operating a suitable form of indicator.

The novel features which I believe to be characteristic of my' invention are Aset forth with. particularity in the appended claims.

My' invention itself, however, both as to its organization and method of operation will. bcstbe understood by reference to the fol-4 Liemeel Tear orifice; vj

cnannm A. Home, or'scnnnncranv, new Yoan, estenos To GENERAL mmc As indicated in the drawing, radio gig.

nals received'upon the antenna 1 are impressedby means of a coupling transformer 2 upon the input. circuit of an electron dis#v charge amplifier 3. The amplified signaling' current, inthe output circuit of amplifier 3 isimpressed by means of a` couplinv transformer 4 upon a circuit which incluides two photoelectric cells 5 and 6. Each of these cells comprises a cathode of a material such as sodium or potassium which has the'property or emittingelectrons when subjected to `the iniuence of light and a cooperating anode enclosed in an evacuated receptacle.

-The two cells are oppositely connected in the circuit so that when both are illuminated current will flow in both directions through the circuit. The receptacles of5 and 6 are enclosed in alight proof .casing or are covered with' some op ue material except for small windows which are opposite slits 7 in the plates 8. As a means Vfor illumm'ating the cells two incandescent lamps 9 are provided which areso arranged that the light therefrom will pass through lenses 10 and fall upon the slits 7. Between the `lamps 9 and the cells, a Vdisc 1 1 with openings 12 therein is interposed so that' when thc disc is rotated by means of a motor 13 the illumination of the two cells will be simultaneousl and periodically interrupted. Each of t e ycells has in circuit therewith a source of' potential 14 which is connected to the 'cells through resistances 15 for ad- ]us'ting the current through the cells to a, point on the operating characteristic where the current will be most sensitive to changes in the potential applied to the cell.' Choke coils 16, which' are inserted in the suppl circuits prevent the high frequency signa ing currents from {iowmg in these circuits and condensers 17 in the circuit upon which the signaling currents are impressed prevent the sources of potential 14 from being short circuited through the signaling cir cuit. The circuit upon which the signaling 'currents are impressed may also include any desired form of indicating device. In the present case,"I have 'shown af pair of telephone receivers 18which are associated with the signa-ling' circuit by means of a trans-v former 19. The primary of this transformer is shun-ted by a condenser 20 for'by-passing the high frequency component of the signaling current.'l n

g y 'Y 1,487,988

Thesystem which I have described may be operated in a variety of ivays. The sources of potential 14 and resistances 15 should be so fad-'usted that the normal cur- 5 rent-s through t e tivo cells are equal. In

`the absence of any signaling potentials no current `Will then be roduced in the signab fingA ciicuit. If signalling potentials ai@ impressed on the circuit and the disc 12 is rotated at such a speed that the illumination of the cells is interrupted at an audio frequency the high frequency signalin oscillations flowing in the circuit connect to the cells will be broken up into audio frequency groups. In this case of course it will neceary to. employ some form of rectifyiiig device in order to reduce a current capable of giving anv audible indication in a telephone receiver. Preferably, however, the disc 124 should be rotated at such'a speed that the illumina tion of the cells is interrupted at a radio frequency. If this frequency corresponds to the signaling frequency land the relations between the signaling. potentials and the time of interruption are so fixed that the periods of illumination correspond with y the periods of potentiel impulses of one polarity, all current impulses of one polarity will be allowed to flow through the circuit and all current imf pulses of the opposite polarity will be substantially suppressed. In this Way a prac-v tically completerectication may be obtained' and the resulting current will be a pulsating direct current. continuous wave telegraphic signals the pulsations'of 'this current will all be of high frequency and no audible indication will be produced by the current in a telephone receiver.- Such a current, however, may be employed to produce an indication in a photographic recorder or other indicating device which is -operable by a steady direct current.

Because of the ditliculty of keeping the speed of the disc at such a value that the interruptions will occur in synchronisin with the signaling wave as well as the'factthat the current provided in this Way does not give an audible indication in a telephone receiver, it will usually be found desirable to rotate the disc at such a speed that the interruptions of the illumination of the cells occur at a frequency differing from the signaling frequency by a frequency within the l ,range of audibility. Under thesecircum- I stances the resulting'pulsating current will Abe capable of producing an indication in the telephone receiver as it will be made up of groups of high frequency impulses of varying amplitude and opposite polarities fol-` lowing` one another at an audible rate.

While I have shown end described only '65 one embodiment of my invention, it will In the case of.

apparent that many modications in the form of apparatus employed and the atrangement thereof may be made without dec parting from the scope of my invention as set forth in the appended claims. 7

What I claimas new and desire to secure byLetters Patent of thc- United Statesfs:

1. Means for detectingr high frequer'zy signals comprising a circuit upon which signaling currents may be impressed, alight i sensitive cell in" said circuit, indicating means associated with said circuit, a source V4of light arranged to illuminate said cell, and

means for periodically interrupting the illu mination of said cell. so

`means associated with said circuit, a source of light arranged to illuminate said cell and means for periodically interrupting the illu-h mination of said cell at a frequency differing from .the frequency of the signaling currents. Y A

4. Means for detecting high. frequency 10 signals comprising a circuit upon which signaling currents may be impressed, a. light sensitive cell in said circuit, indicating means associated with said circuit, a source of light arranged to illuminate said cell, and means forperiodically interrupting the illumination of said cell at a frequency differing from the frequency of the signaling currents by a frequency` within the range of audibility. 110

5, Means for detecting high frequency signals comprising a circuit upon which signaling currents may be impressed, a light sensitive cell in said circuit, indicating means associated .with said circuit. a source of light arranged to illuminate said cell, and means independent of the signaling currents for periodically interrupting the illumination of said cell at a frequency difering from the frequency of the signaling cur-l rents.

6. kMeans for detecting high frequenc signals comprising a circuit upon Wliic signaling currents may be impressed, a.

light sensitive cell in said circuit, indicati 125.. `im; meansaassociatedwith said circuit, a

source of light arranged to illuminate said- Y, cell, and means independent of the signaling currents for periodically interrupting the illumination of said cell at a frequency inertes ldiffering from the frequency of the signalysignals comprising a circuit upon which `signaling currents may be impressed, a device in'said circuit having a cathodecapable ofemitting electrons when subjected to the influence of light and an anode, indicating means associated with said circuit, a source of light arranged `to illuminate said cathode, and kmeans for periodically interrupting the illumination of said cathode.

- 8.- Means for detecting high frequency signals comprising a circuit upon which signaling' currents may be impressed, a device in said circuit having a cathode capable of emitting electrons when subjected to the influence of light and an anode, in-- dicating means associated with said circuit, a source of light arranged to illuminate said cathode, and means independent of the sig-l naling currents for periodically interrupting the illumination of said-cathode,

A9. Means for detecting high frequency signals comprising a circuit upon which signaling currents may be impressed, a device in said'circuit having acathode capablo of emitting electrons when subjected to the influence of light and an anode, indicating ineens associated with said circuit, a source of light arranged to illuminate saidcathode, and means for periodically interrupting the illumination 'of said cathode at a frequency differing from the frequencyof the signaling currents. v

10. Means for detecting high frequency signals comprising a circuit upon which signaling currents may be impressed, a device in said circuit having a cathode capable -of emitting electrons when subjected to the infiuence o-light and an anode, indicating means amociated with said circuit, a source of light arranged to illuminate said cathode, and means for periodically interrupting the illumination of said cathode at a frequency differing from the frequency of the signaling currents by a frequency within the range. of audibility.-

` 11. Means for detecting high frequency signals `coinprisingu circuit upon whichsignaling currents maybe impressed, a device in said circuit having a cathode capable of emitting electrons when subjected to the inluence cf light and an anode, indicating means associated with said circuit, a source of light arranged to illuminate said cathode,

and -means independent of thesgnaling currents .for periodicallyinterrupting the illumination of said cathode at a frequency differing from the frequency of the signaling currents.

12. Means for, detecting-high frequency signals comprising a circuit upon which signaling currentsmay be impressed, a derange of audibility.

vice in said circuit having a cathode capable of emitting electrons when subjected to the f iniiuence of light and an anode,indicating means associated VWith said circuit, a. source of light arranged to illuminate said cathode, and means independent of the signaling currents for periodically interrupting the illuminatin of said cathode at a frequenc diiering from the frequency of the signa ing currents by 'a frequency within the 13. Means for detecting high frequency signals comprising` a circuit upon which signaling currents may beimpressed',l a device vin saidcircuit having a cathode. capable of emitting electrons when subjected to the in-A luence of light and an anode', indicating mea-ns associated with said circuit, a source of light arranged to illuminate said cathode and a disc with openings Atherein interposed between said light source and said cathode, and'means for rotating said-disc.

7,14'. Means for detecting high frequenc signals comprising a circuit upon whi signaling currents may be impressed, a device in said circuit having a cathode capable of emitting electrons when subjected to the iniluence of light and an anode, indicating means associated with saidcircuit, a source of light arranged to illuminate said cathode, a disc with openings therein interposed between said light source and said cathode, and means for rotating said disc at such al speed that the light passing thru said o enings and falling on said cathode will) be periodically interrupted.

15. Means for detecting high frequenc signals comprisingA a circuit upon whic signaling currents may be impressed, a de- Yvice in said circuit having a cathode capable of emitting electrons when subjected to the influence of light and an anode, indicating means associated with said circuit, a source of light arranged to illuminate said cathode, a disc with openings therein interposed between said light source and said cathode, and means for rotating said disca-t such a s that the lig-ht passing thru said openings and falling on said' cathode will be periodically interrupted at so 'A ico a. frequency differing from the frequency A to the inluence of light and an unodeh y indicating means lassociated with said circuit,a source of li ht arranged yto illuminate said cathode, a disc with openings therein interpod between said light source and f said cathode, and means for rot-ating said disc at such a speed that the light paming thru said openings and falling on said .130

cauiode will 'be periodically interrupt@ si a. frequency differing from the frequency of the signaling currents by a. frequency -Wit-hin the range of audibility.

, both of said cells and means for periodically interru ting the illumination of szlidfcells.

18. lv'eans for detecting high frequenc signals comprising a. circuit upon Whicsignaling currents my be impressed, a. pair of light sensitive cells oppositely connected in said circuit, indicating means' associated. with said circuit, means for illuminating bothof said cells land means for periodically interrupting the illumination of said cells at a frequency differing from the frequency of the signaling currents.

19. Means for detecting high frequency signals comprising n circuit upon which signaling currents may be impressed, a pair of light'sensitive cells oppositely connected in sirid circuit, indicating means associu'ted with rwid circuit, means for illuminatingI both of said cells and means for periodically'T interrupting the illumination of said' cells by bllity.

at a frequencv differing from the frequency of the signaling currents' by a' frequency within the ranfge of audi'bility.

20. Means or detecting high frequency signals comprising e :circuit upon which signaling currents may beixnpressed, a pair of light sensitive cells oppositely connected in said circuit, indicating means associated both of seid cells and means for periodically and 'simultaneously interrupting 'the illumination of seid cells. i

21. Means for detecting high frequenc signals comprising ii.A circuit upon whic signaling currents may be impressed, s. pair of light sensitive cells oppositely connectedv in seid circuit, indicating means associated with said circuit, lne-uns for illulininlitinglv both of said cells end lne-ens forperiodicall and simultaneously interrupting the illumination of seid cells at s frequency differingand silliultuneously interrupting the illumi-v nation of said cells at e frequency differing with said circuit, 'means for illuminating from the frequency of the signaling currents l a frequency within the range of audi.-

In Witness whereof, I have hereuntoset my hand this 9th dey of March v1922'. Y

CHARLESA. HOXIE. Y 

